Recently we had to migrate a Scalix installation from Fedora to Xandros Server and at the same time upgrade from 11.0.1 to 11.3. The site had over 200 user accounts. At first I thought this would be a difficult task but it turned out to be relatively simple thanks to the fact that, being a minor version upgrade there was no major changes in the database and file structure.
Mark Clarke's blog
Sometime solutions that are obvious are difficult to see because you image the solution must be much harder than it really is. Recently I had to recover a forgotten root password for a virtual domain, DomU, on a Xen box for one of our clients.
If you have ever visited the Java Developer Journal web site you have had to contend with their annoying popup ad that blocks the whole screen until you click "close window". Whilst I support the need for sites to make money from advertising the lengths that sys-con go to is just a darn right abuse of Internet users. In fact its the whole of the sys-con.com and its subdomain that employ this type of spamming.
Recently one of our client's old AIX boxes, which had been reduced to being a server for some old Sunix dumb terminals, after its heyday as the financial system server, died on them leaving their warehouse without computer access.
Recently I have had to assist two friends with systems that were borked to the point of no longer being bootable. In both cases there had been warning signs that there was impending doom, like the machine spontaneously rebooting, or having to cold boot the laptop several times to get it to the windows login prompt.
A few months ago I setup a new computer for my 73 year Mother and instead of installing Windows I decided to put Linux on the box. I wrestled with doing this for a while as I didn't want to have my Mom getting confused with a new interface. Previously windows had been installed on the old box. Another factor was that I am in Johannesburg while my Mom and Dad are in Durban.
Today we experienced some mail delivery problems on one of our client's servers running Centos 4 and postfix with amavisd for virus and spam scanning.
Trawl the log files
The mail logs where filling with errors such as:
(delivery temporarily suspended: lost connection with 127.0.0.1[127.0.0.1] while sending RCPT TO)
Java Persistence API detached object gotchas
One of the issues to get your head around in both Hibernate and JPA is how to handle detached entities. In Hibernate one has to deal with the session object and in JPA it is called the persistence context.
A common error when using EJB3 is
Cannot find the declaration of element 'persistence'
This is caused by a missing xml namespace attribute declaration in your persistence.xml file. To fix this error make sure your persistence tag has the following syntax:
<persistence xmlns="http://java.sun.com/xml/ns/persistence" version="1.0">